As many of these posts seems simalar, but with slight variations, I will share my issues and my work-around.
2 computers-(business) Dell 630 with docking station/port replicator running Win7 enterprise, Self built tower with AMD chipset and GeForce 7300 graphics card running Win7Home Premium.
I am running 3 monitors sharing a central monitor on on both computers. When switching to my homesystem, it flips to the shared (KVM) monitor as a single monitor. When switching to the Dell D630, everything works perfectly.
Work-around: Open the NVidia Control Panel and everything corrects itself. There have never been any resolution changes, just the loss of dual monitors when switching to the home system.
I have tried many of the thoughts in this thread that seem to be similar issues with no louck. I suppose just having to open the NVidia control panel and close it is easier/cheaper than many others options, I will live with it until MS decides to action this issue.